To accomplish the trick, the researchers used a microphone to record the noises made by the computer, then ran that audio through filters to isolate the vibrations made by the electronic internals during the decryption process

There are a number of really good reasons why this isn't likely, but the best is just math:

A microphone can 'record' anywhere from 20 to 20KHz. Really, really good microphones can expand that range somewhat, but no audible microphone is going to be able to do much to expand that range.

Another option is to use a laser and bounce that off of the device and measure how much variation the bounced light has to recreate the signal, and that might allow for better resolution, but I'm going to go out on a limb here and speculate that it won't have the ability to take accurate samples at the Gigahertz rate it would require.

But suppose you had an accurate mic that could record sound waves at 1-4Ghz, the next problem is propagation through the air. Does 1-4Ghz sound vibrate enough through the air to be detected by a recording device? How powerful does it have to be in order to do this? 1-4Ghz seems to dance all over the spectrum used for WiFi, so I'm wondering if the 'sound' of the computer operating would even be hearable over the deafening roar of all the 802.11a, b, and n antennas in the area.

But lastly, we come to the idea that computer circuits make noise due to vibration. I'm sure someone will show me that atoms are just made up of strings that vibrate and the universe is just a symphony of vibrations in harmony that make up our reality, but

@ScanIAm:well, you can email that to the university that conducts the research. I am not an acoustic professional, so, I do not know how to verify their work. So, what you are saying is, with your knowledge of how mic works, you do not believe the mic is capable of receiving the sound. I am quite sure they wouldn't start the research if they haven't figure that out. Most likely, their paper is build upon the ability to listen the sound from an already validated scientific paper, which can be found in the reference section, which also likely have have sizable citations. I will try trace it once I get home. In the meantime, it would be nice to read the article and feel the magic.

this side-channel mitigation in GnuPG actually helps our attack, by increasing the aforementioned amplification of the innermost loop.

When you do, you'll see they specifically point out every issue I've called into question as well.

What they have done is exploit the coding of an algorithm in a specific version of some obscure software that causes a tight loop to occur under known conditions. This loop lasts long enough that it can be detected by listening to the noise created by the voltage regulators. The result of this has the effect of making the computer yell out each bit of the key very, very slowly so that it can be recorded. This is not something that is going to render computers hackable with a cellphone mic and some patience.

Then, they shift, very quickly, to a much more realistic method of doing this that involves measuring the ground voltage which one could easily do given access to the machine. But then, if you had access to the machine....

@ScanIAm:so basically implanting a bug will be able to listen to it at certain top secret agency. While the user has no actual knowledge of keys content, the bug can listen to the computer-only key yelling. And since the person who implemented the bug already knows what the standard software target used to decrypt files, it is easy to train the bug to listen to those yelling beforehand. Interesting.

I believe the agency should patch this problem. However, the chances are, they are not going to patch it within the next 20 years, until they realized the leakage is very severe. Given government's reaction speed and awareness level, this is a possible scenario.

Not really. It's mostly theoretical at the moment, it requires an incredibly powerful microphone, placed very close to the computer and then a series of carefully constructed "known" information being sent encrypted in order to extract the key being used for decryption. It's not something that could happen, currently, without you being very aware of it.

It does however highlight one of the real problems with computer security that is often overlooked, or considered so fantastical that it gets dismissed too quickly, namely the information that 'leaks' out of seemingly innocuous side channels when data is being processed. Whether it's as complicated as the example here, or as simple as noticing the difference in response times evident in a security handshake (e.g. does a invalid username respond quicker than a valid username with an incorrect password) - the amount of information that can be inadvertently given to the "bad guys" can be quite surprising.

Not really. It's mostly theoretical at the moment, it requires an incredibly powerful microphone, placed very close to the computer and then a series of carefully constructed "known" information being sent encrypted in order to extract the key being used for decryption. It's not something that could happen, currently, without you being very aware of it.

Err... you didn't read it, did you?

Here, we describe a new acoustic cryptanalysis key extraction attack, applicable to GnuPG's current implementation of RSA. The attack can extract full 4096-bit RSA decryption keys from laptop computers (of various models), within an hour, using the sound generated by the computer during the decryption of some chosen ciphertexts. We experimentally demonstrate that such attacks can be carried out, using either a plain mobile phone placed next to the computer, or a more sensitive microphone placed 4 meters away.

Also I'm not entirely sure why people are talking about the NSA here. This is a research paper from Tel Aviv University; nothing to do with the NSA.

@JoshRoss: Cool story as it sounds completely plausible. Bit disappointing that he's some supposedly famous security guy and yet from the article and his postings sounded like he's having difficulties producing something more substantive. The few security bloggers I've read know how to analyze bus communication and firmware code, so if he doesn't, you'd think he'd got some help to do it by now but it was written like this wasn't even being looked into. Weird.

@evildictaitor:nah, it hasn't made into NSA 10.01 YET, assuming we are at NSA 1.0 or 2.0, I am just doing baseless chatter here. But, I do think it will be be a great movie material that is likely ended up as reality.

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